1. Field of the Invention
The invention relates to an optical scanner altering an angle of a reflective surface reflecting the incoming light, relative to an entry direction in which the incoming light enters the reflective surface, to thereby scan reflected light from the reflective surface, and more particularly to technologies of controlling the intensity of the reflected light from the reflective surface.
2. Description of the Related Art
There are known as optical scanners for scanning light, such a type of an optical scanner that alters an angle of a reflective surface reflecting the incoming light, relative to an entry direction in which the incoming light enters the reflective surface, to thereby scan the reflected light from the reflective surface. See, for example, Japanese Patent Application Publication No. HEI 11-203383.
Such an optical scanner is used in many various fields, such as image forming, and image reading. In the field of image forming, such an optical scanner is applied to retinal scanning type display devices which scan a beam of light on the retina of a viewer for direct presentation of a desired image onto the retina; projectors; laser printers; devices for use in laser lithography; or other applications. In the field of image reading, such an optical scanner is applied to facsimile machines; copiers; image scanners; bar-code readers; or other applications.
An example of such an optical scanner is of a type in which oscillation of a reflective surface achieves the scanning of light. Another example of such an optical scanner is of a type in which unidirectional rotation of a reflective surface achieves the scanning of light.
As disclosed in Japanese Patent Application Publication No. HEI 11-203383, an example of the above-described oscillating type optical scanner is constructed to include a mirror for reflecting light; and a vibrating body for torsion-vibrating the mirror.
While this example falls within a type of an optical scanner that performs the oscillation of a reflective surface through its vibration, there exists an alternative type of an optical scanner that performs the oscillation of a reflective surface without through its vibration. A more specific example of the alternative type is an optical scanner utilizing a galvano mirror.
In contrast, an example of the above-described rotating type optical scanner is constructed to utilize a polygon mirror having a plurality of adjacent mirror facets in succession around the polygon mirror. The optical scanner utilizing the polygon mirror differs in that successive uses of the plurality of mirror facets achieve repeated scans, from the optical scanner oscillating a reflective surface in which continuous use of the same reflective surface achieves repeated scans.